Secondary wetting

Introducing the Young equation into (H. 1) and setting d( 5Fs)/d( Sx) = 0, shows that infiltration is possible if the experimental dihedral angle is lower than the value a given by  

Conversely, in the Cu / W system for which Lorrain (1996) found a contact angle of 50° at 1100°C, secondary wetting was not observed, even after one hour at this temperature. Indeed, for this sytem, the experimental value of O (see Table 4.4) is much higher than the value a = 69° calculated from equation (H.2) taking 0Y = 50°. 

The thermodynamic condition for secondary wetting described by equation (H.2) is expected to hold for many metal combinations and more seldomly for metal/ceramic couples. In practice, a detailed study of this phenomenon is difficult to perform because other phenomena can complicate the analysis. For example, dissolution of the solid in the liquid or diffusion of a component of the liquid in the solid could occur during prolonged experiments. In the last case, the liquid volume 

Lequeux, S., Le Guyadec, F., Berardo, M., Coudurier, L. and Eustathopoulos, N. (1998) in Proc. 2nd Int. Conf. on High Temperature Capillarity, Cracow (Poland), 29 June-2 July 1997, ed. N. Eustathopoulos and N. Sobczak, published by Foundry Research Institute (Cracow), p. 112 

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A Remark on Systems Exhibiting Primary and Secondary Wetting... 

One interpretation of systems that exhibit primary and secondary wetting regimes is that the primary spreading occurs nominally without physicochemical interaction with the S/L boundary (similar to inert wetting) and approaches a quasi-equiUbrium in which where 0qe... 

Primary vs. secondary wetting—Grain boundary enhancement of wetting is often... 

In the case of solvent spinning, ie, secondary acetate, polyacrylonitrile, and poly(vinyl chloride), the FWA is added to the polymer solution. An exception is gel-whitening of polyacrylonitrile, where the wet tow is treated after spinning in a washbath containing FWA. 

Wet chemical methods determining titratable amine ate reported for products entering urethane (amine number as meq/g) or epoxy (AHEW = amine hydrogen equivalent weight) trade appHcations. For secondary amines /V-nitrosamine contaminants are reportable down to ppb using Thermoelectron Corporation thermal energy analy2er techniques. 

To analy2e fatty amines, both wet and instmmental methods of analysis are used. Wet methods routinely used are total amine value (ASTM Method D2073) combining weight or neutralization equivalent primary, secondary, and tertiary amine content (ASTM Method D2083) moisture, Kad-Fischer (ASTM Method D2072) and iodine value, measure of unsaturation (ASTM Method D2075). These provide important information on physical and chemical characteristics of the amine products used in various appHcation areas (8,76,81). In addition to the ASTM methods available, the American Oil Chemists Society has developed methods of analysis for fatty amines (82). 

Multicompartmented mills feature grinding of coarse feed to finished produc-t in a single operation, wet or dry. The primary grinding compartment carries large grinding balls or rods one or more secondary compartments cany smaller media for finer grinding. 

Cement plants Quarrying primary crusher, secondary crusher, conveying, storage Particulates (dust) Wetting exhaust systems with fabric filters... 

The output from oil fields, after secondary and tertiary processing [7], is considered wet oil. It consists of oil field brine, crude oil and natural gases containing a high COj content and in certain circumstances it may also contain small amounts of H2S. Wet oil can also contain solid particles from the bedrock. 

Calcium oxide (lime) Rotary kilns, vertical and shaft kilns, fluidized bed furnaces Particulate matter Cyclones plus secondary collectors (baghouse, ESP, wet scrubbers, granular bed filters, wet cyclones)... 

Wet scrubbers rely on a liquid spray to remove dust particles from a gas stream. They are primarily used to remove gaseous emissions, with particulate control a secondary function. The major types are venturi scrubbers, jet (fume) scrubbers, and spray towers or chambers. Venturi scrubbers consume large quantities of scrubbing liquid (such as water) and electric power and incur high pressure drops. Jet or fume scrubbers rely on the kinetic energy of the liquid stream. The typical removal efficiency of a jet or fume scrubber (for particles 10 g. or less) is lower than that of a venturi scrubber. Spray towers can handle larger gas flows with minimal pressure drop and are therefore often used as precoolers. Because wet scrubbers may contribute to corrosion, removal of water from the effluent gas of the scrubbers may be necessary. 

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